The ancient civilization known for its complex social hierarchies and religion is Mesopotamia. Emerging around 3500 BCE, this region, situated between the Tigris and Euphrates rivers, comprised several city-states such as Sumer, Akkad, Babylon, and Assyria. Mesopotamian society was highly stratified, with a clear hierarchy that included kings, priests, merchants, and farmers. Their polytheistic religion involved numerous gods associated with natural elements and city-states. Temples, or ziggurats, were the center of religious and administrative activities. The civilization made significant advancements in writing, mathematics, and law, exemplified by the Code of Hammurabi, influencing subsequent cultures.